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6560-50

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52 [EPA-R08-OAR-2006-0952; FRL-9200-9]
Air Quality Implementation Plans; Montana; Attainme nt Plan for Libby, MT PM 2.5 Nonattainment Area and PM 10 State Implementation Plan Revisions AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is proposing to approve the State Implementati on Plan (SIP) revision submitted by the State of Montana on March 26, 2008 . Montana submitted this SIP revision to meet Clean Air Act requirements for attaining the 1 5.0 micrograms per cubic meter (μg/m 3 ) annual fine Particulate Matter (PM 2.5 ) national ambient air quality standard (NAAQS) for t he Libby nonattainment area. The plan, herein called an “attainment plan,” includes an attainment demonstration, an analysis of Reasonably Available Control Technology and Reasonably Available Control Measures (RACT/RACM), base-year a nd projection year emission inventories, and contingency measures. The require ment for a Reasonable Further Progress (RFP) plan is satisfied because Montana projects th at attainment with the 1997 PM 2.5 NAAQS will occur in the Libby nonattainment area by April 2010. In addition, we are proposing to approve the PM 10 SIP revisions to the Lincoln County Air Pollution Control Program submitted by Montana on June 26, 2006 for inclusion into Libb y’s attainment plan. This submittal contains provisions, including contingency measures, for con trolling both PM 10 and PM 2.5 emissions from woodstoves, road dust, and outdoor burning. Finall y, EPA is proposing to find on-road directly emitted PM 2.5 and oxides of nitrogen (NO x ) in the Libby, Montana nonattainment area2 of 52

insignificant for regional transportation conformit y purposes. If this insignificance finding is finalized as proposed, the Libby, Montana nonattain ment area will not have to perform a regional emissions analysis for either direct PM 2.5 or NO x as part of future conformity determinations for the annual 1997 PM 2.5 NAAQS.

DATES: Written comments must be received on or before [Insert date 30 days after publication in the Federal Register ]

.

ADDRESSES : Submit your comments, identified by Docket ID No . EPA-R08-OAR-2006- 0952, by one of the following methods:

• www.regulations.gov . Follow the on-line instructions for submitting c omments.

• E-mail: freeman.crystal@epa.gov

• Fax: (303) 312-6064 (please alert the individual l isted in FOR FURTHER INFORMATION CONTACT if you are faxing comments).

• Mail: Callie Videtich, Director, Air Program, Envi ronmental Protection Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop St., Denver, Colorado 80202- 1129.

• Hand Delivery: Callie Videtich, Director, Air Prog ram, Environmental Protection Agency (EPA), Region 8, Mail Code 8P-AR, 1595 Wynko op St., Denver, Colorado 80202-1129. Such deliveries are only acce pted Monday through Friday, 8:00 a.m. to 4:30 p.m., excluding Federal holidays. Special arrangements should be made for deliveries of boxed information.3 of 52

Instructions: Direct your comments to Docket ID No. EPA-R08-OAR -2006-0952. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at www.regulations.gov , including any personal information provided, unless the comment includes information c laimed to be Confidential Business Information (CBI) or other information whose disclo sure is restricted by statute. Do not submit information that you consider to be CBI or otherwis e protected through www.regulations.gov or e-mail. The www.regulations.gov web site is an anonymous access system, which mean s EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA, without going through www.regulations.gov , your e-mail address will be automatically capture d and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that y ou include your name and other contact information in the body of your comment and with an y disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficult ies and cannot contact you for clarification, EPA may not be able to consider your comment. Elec tronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA’s public docket, visit the EP A Docket Center homepage at http://www.epa.gov/epahome/dockets.htm . For additional instructions on submitting commen ts, go to Section I, “General Information,” of the SUPPLEMENTARY INFORMATION section of this document. Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not public ly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material,4 of 52

will be publicly available only in hard copy. Publ icly available docket materials are available either electronically in www.regulations.gov or in hard copy at the Air Program, Environmental Protection Agency (EPA), Region 8, 1595 Wynkoop St. , Denver, Colorado 80202-1129. EPA requests that, if at all possible, you contact the individual listed in FOR FURTHER INFORMATION CONTACT to view the hard copy of the docket. You may view the hard copy of the docket Monday through Friday, 8:00 a.m. to 4:00 p.m., excluding Federal holidays.

FOR FURTHER INFORMATION CONTACT: Crystal Freeman, Air Program, Environmental Protection Agency (EPA), Region 8, Ma ilcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado 80202-1129, Phone: (303) 312-6602, Fax: (303) 312-6064, freeman.crystal@epa.gov.

SUPPLEMENTARY INFORMATION: Definitions For the purpose of this document, we are giving mea ning to certain words or initials as follows: (i) The words or initials Act or CAA mean or refer to the Clean Air Act, unless the con text indicates otherwise. (ii) The words EPA, we, us or our mean or refer to the United States Environmental P rotection Agency. (iii) The initials SIP mean or refer to State Implementation Plan. (iv) The initials PM 2.5 mean or refer to particulate matter with an aerody namic diameter of less than 2.5 micrometers. (v) The initials PM 10 mean or refer to particulate matter with an aerody namic diameter of less than 10 micrometers.5 of 52

(vi) The word State or Montana refers to the State of Montana unless the context indicates otherwise. (vii) The initials NAAQS

mean or refer to National Ambient Air Quality Stan dards.

Table of Contents I. General Information II. What Action Is EPA Proposing? III. What Is the Background for EPA’s Proposed Acti on? A. Designation History B. Clean Air Fine Particle Implementation Rule IV. What Is Included in Montana’s Submittal? A. Background
B. PM 10 SIP Revisions to the Lincoln County Air Pollution Control Program C. Libby and Vicinity PM 2.5 Control Plan V. EPA's Analysis of Montana’s Submittal
A. PM 10 SIP Revisions to Lincoln County Air Pollution Cont rol Program B. Attainment Demonstration C. Analysis of Montana’s Submittal 1. Pollutants Addressed and Attainment Date 2. Monitoring Data 3. Emission Inventory 4. Modeling 5. RACT/RACM6 of 52

6. Contingency Measures 7. Transportation Conformity Requirements VI. Proposed Action VII. Statutory and Executive Order Reviews

I. General Information A. What Should I Consider as I Prepare My Comments for EPA?
1. Submitting CBI. Do not submit this information to EPA through www.regulations.gov or e-mail. Clearly mark the part or all of the inf ormation that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EP A, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for in clusion in the public docket. Information so marked will not be disclosed except in accordance w ith procedures set forth in 40 CFR part 2.
2. Tips for Preparing Your Comments. When submitting comments, remember to:

a. Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date and page number). b. Follow directions - The agency may ask you to respo nd to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.

c. Explain why you agree or disagree; suggest alternat ives and substitute language for your requested changes.7 of 52

d. Describe any assumptions and provide any technical information and/or data that you used.

e. If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced. f. Provide specific examples to illustrate your concer ns, and suggest alternatives.
g. Explain your views as clearly as possible, avoiding the use of profanity or personal threats. h. Make sure to submit your comments by the comment pe riod deadline identified.

II. What Action Is EPA Proposing? EPA is proposing to approve two Montana SIP submit tals for the Libby nonattainment area: (1) PM 10 SIP revisions to the Lincoln County Air Pollution Control Program submitted by Montana on June 26, 2006; and (2) the Libby PM 2.5 attainment plan submitted by Montana on March 26, 2008. EPA has determined that the PM 10 SIP revisions and the PM 2.5 attainment plan meet applicable requirements of the Clean Air Act, including the Clean Air Fine Particle Implementation Rule (herein referred to as the impl ementation rule) issued by EPA on April 25, 2007 (72 FR 20586). Furthermore, EPA has determine d that Montana’s PM 2.5 SIP submittal for the Libby area includes an attainment demonstration , an analysis of RACT/RACM, base-year and projection-year emission inventories and contin gency measures. The attainment plan supports a determination that the Libby PM 2.5 nonattainment area will attain the 1997 PM 2.5 NAAQS by the April 2010 deadline for attainment. F inally, EPA is proposing to find on-road directly emitted PM 2.5 and NO x in the Libby, Montana nonattainment area insignifi cant for regional transportation conformity purposes.8 of 52

EPA’s analysis and findings are discussed in this p roposed rulemaking. Additional technical support documents are available at www.regulations.gov , Docket No. EPA-R08-OAR-2006- 0952.

III. What Is the Background for EPA’s Proposed Action? A. Designation History On July 18, 1997 (62 FR 38652), EPA established PM 2.5 NAAQS, including an annual
standard of 15.0 μ g/m 3 based on a 3-year average of annual mean PM 2.5 concentrations, and a 24- hour (or daily) standard of 65 μ g/m 3 based on a 3-year average of the 98th percentile o f 24-hour
concentrations. EPA established the standards base d on significant evidence and numerous health studies demonstrating that serious health ef fects are associated with exposures to PM 2.5 .

Following promulgation of a new or revised NAAQS, EPA is required by the CAA to designate areas throughout the United States as att aining or not attaining the NAAQS; this designation process is described in section 107(d)( 1) of the CAA. In 1999, EPA and state air quality agencies initiated the monitoring process f or the 1997 PM 2.5 NAAQS, and, by January 2001, established a complete set of air quality mon itors. On January 5, 2005, EPA published initial air quality designations for the 1997 PM 2.5 NAAQS (70 FR 944), based on air quality monitoring data for calendar years 2001-2003. On A pril 14, 2005, EPA published a final supplemental rule amending the agency’s initial des ignations (70 FR 19844). EPA did not consider modifications made in this rule to be “re- designations” because the changes were made before April 5, 2005, the effective date of the ini tial designations. As a result of the final9 of 52

supplemental rule, PM 2.5 nonattainment designations are in effect for 39 ar eas, comprising 208 counties within 20 states (and the District of Colu mbia) nationwide, with a combined population of about 88 million people. The Libby nonattainmen t area which is the subject of this rulemaking is included in the list of areas not att aining the 1997 PM 2.5 NAAQS.

On October 17, 2006, EPA strengthened the 24-hour PM 2.5 NAAQS to 35 μg/m 3 and retained the level of the annual PM 2.5 standard at 15.0 μg/m 3 (71 FR 61144). On November 13, 2009 EPA designated areas as either attainment/uncl assified or nonattainment with respect to the revised 24-hour NAAQS (74 FR 58688). In the Novemb er 2009 designation action, EPA established a deadline of December 14, 2012 for sta tes to submit attainment plans for areas designated as nonattainment for the revised 24-hour PM 2.5 NAAQS.

Of relevance to the proposed rulemaking herein, th e notice for the November 2009 action clarified designations for the 1997 PM 2.5 NAAQS by relabeling the existing designation table s to identify designations for the annual NAAQS, and by providing a separate table identifying designations for the 1997 24-hour NAAQS (i.e. 65 μg /m 3 ). In that table, the Libby nonattainment area is designated as attaining the 1 997 24-hour PM 2.5 NAAQS.

B. Clean Air Fine Particle Implementation Rule On April 25, 2007, EPA issued the Clean Air Fine Pa rticle Implementation Rule for the 1997 PM 2.5 NAAQS (72 FR 20586). The implementation rule desc ribes the CAA framework and requirements for developing state PM 2.5 attainment plans. An attainment plan must include a demonstration that a nonattainment area will meet a pplicable NAAQS within the timeframe10 of 52

provided in the statute. This demonstration must i nclude modeling (40 CFR 51.1007) that is performed in accordance with EPA modeling guidance (EPA-454/B-07-002, April 2007). It must also include supporting technical analyses and descriptions of all relevant adopted federal, state, and local regulations and control measures t hat have been implemented by the proposed attainment date.

For the 1997 PM 2.5 NAAQS, an attainment plan must show that a nonattai nment area will attain the standard by 2010. Alternatively, if the area is not expected to meet the NAAQS by 2010, a state may propose an attainment-date extens ion for up to five years based on the severity of the nonattainment problem and on the availabilit y and feasibility of pollution control measures (CAA section 172(a)(2)).

For each nonattainment area, the state must demonst rate that it has adopted all RACT/RACM needed to show that the area will attain the PM 2.5 standards “as expeditiously as practicable.” The implementation rule provided gui dance for making these RACM and RACT determinations (72 FR 20616-21). Any measures that are necessary to meet these requirements which are not already either federally promulgated or part of the state’s SIP must be submitted in enforceable form as part of a state’s attainment pl an.

The implementation rule also included policies on p ollutants that comprise total PM 2.5. Five main types of pollutants contribute to fine pa rticle concentrations: direct PM 2.5 , sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), ammonia, and volatile organic compounds (VOCs). All but direct PM 2.5 is considered to be “precursors” to PM 2.5 formation. The effect of reducing11 of 52

emissions of each of these five types of pollutants varies by area, depending on PM 2.5 composition, emission levels, and other area-specif ic factors. For this reason, the implementation rule established policies regarding what states should include in their PM 2.5 attainment plans for evaluating these pollutants.

Under these policies, sources of direct PM 2.5 emissions (including organic particles, elemental carbon and inorganic particles) and SO 2 must be evaluated for emission reduction measures in all PM 2.5 nonattainment areas. Sources of NO x must be evaluated for emission reduction measures in each area unless the state an d EPA demonstrate that NO x is not a significant contributor to PM 2.5 concentrations in a specific area. Neither VOC no r ammonia sources are required to be evaluated for emission r eduction measures in an area unless the state or EPA demonstrates that either of these pollutant types significantly contributes to PM 2.5 concentrations. To reverse any of the presumptive precursor policies, the implementation rule provided guidance on the types of analyses that may be included in a technical demonstration.

The implementation rule also provided guidance on other elements of a state’s attainment plan, including but not limited to, consideration o f emission inventories, contingency measures, and motor vehicle emissions budgets used for transp ortation conformity purposes.

IV. What Is Included in Montana’s Submittal? A. Background Libby, Montana, a small rural community, is located in Lincoln County in the northwestern part of the State. Libby sits in the narrow, triangular Kootenai valley at an12 of 52

elevation of 2,100 feet. The nonattainment area is dominated by three major mountain ranges that limit the air-shed: (1) the Rocky Mountain and Flathead Ranges on the eastern boundary; (2) the Purcell Range, which roughly bisects the area f rom north to south; and (3) the Selkirk and Cabinet Ranges on the western boundary. The vast m ajority of the area surrounding Libby is National Forest managed by the U.S. Forest Service. Based on the 2000 census and a growth rate through 2005 of 3.71%, Libby’s population is e stimated at 2,674.

The highest PM 2.5 concentrations in Libby generally occur during the winter months of November through February. The winter concentratio ns are related to stagnant weather conditions dominated by light winds and strong temp erature inversions. These meteorological conditions can trap emissions within the valley for many days or weeks.

Air quality data recorded during 2001-2003 at the PM 2.5 monitor at the Libby Courthouse Annex showed violations of the annual PM 2.5 standard. Libby was designated nonattainment for
PM 2.5 under section 107(d)(3) of the CAA, on April 5, 20 05 (40 CFR part 81). The air quality planning requirements for PM 2.5 nonattainment areas are set out in Title I subpart 1 of the Act. 1

Historically, Libby was designated nonattainment f or PM 10 by operation of law on November 15, 1990 (56 FR 56694, 56794, November 6, 1991), under CAA section 107(d)(4)(B) and was classified as ‘Moderate.’ The PM 10 attainment plan was approved by EPA on August 30, 1994 (59 FR 44627). Montana has submitted revi sions to the Lincoln County Air Pollution Control Program (herein referred to as the Program) and the Libby and Vicinity PM 2.5 Control

1 Subpart 1 applies to nonattainment areas generally

.13 of 52

Plan (herein referred to as the Libby attainment pl an) for the purpose of demonstrating attainment of the annual PM 2.5 NAAQS. After public notice, public hearings regard ing these two submittals were held on February 27, 2006 for the L incoln County Air Pollution Control Program and on March 25, 2008 for the Libby and Vic inity PM 2.5 Control Plan. The Montana Board of Environmental Review approved the revised Lincoln County Air Pollution Control Program on March 23, 2006 and the Libby attainment plan on March 25, 2008. Montana has met the requirements of Section 110(a)(2) for reaso nable notice and public hearings.

B. PM 10 SIP Revisions to the Lincoln County Air Pollution Control Program Montana submitted revisions to the PM 10 SIP for the Lincoln County Air Pollution Control Program for the Libby nonattainment area to improve and strengthen the PM 10 attainment plan. The revisions include several pro visions to regulate solid fuel burning devices and require owners and operators to obtain operatin g permits. Operating permits may only be issued for EPA-certified woodstoves or for pellet s toves. Furthermore, only specified materials can be burned in these devices, and visible emissio ns of greater than 20% opacity from them are prohibited. Additionally, these provisions allow f or air pollution alerts if PM 10 or PM 2.5 concentrations averaged over a 4-hour period exceed a level 20 percent below any federal or state particulate matter standard. Provisions are also included for penalties for non-compliance and contingency measures.

Additionally, revisions were made for open and out door burning regarding prohibited materials, major open burning and management burnin g, minor open burning or residential open burning, and special burning. These revisions gene rally included significant limits on the time14 of 52

periods for open burning activities as compared to the existing PM 10 SIP. Further restrictions also include prohibitions on burning from November 1 to March 31, which is the winter-time period when exceedances of PM 2.5 typically occur. Lincoln County’s Program prohibit s burning the same materials as the State but is more restric tive because the burning of trade waste, Christmas tree waste, leaves, grass clippings and s tumps is prohibited within the Air Pollution Control District 2 (herein referred to as the District). The June 26 , 2006 submittal also included a stringency analysis for the Program showing that th e revisions are more stringent than comparable State law.

C. Libby and Vicinity PM 2.5 Control Plan The Libby attainment plan provides a demonstration that the annual PM 2.5 NAAQS will be met by April 2010 through the implementation of the Lincoln County Program described in section B above. The Libby attainment plan include s an emissions inventory (EI), a woodstove air pollution control calculation, and a technical analysis showing that the emissions of PM 2.5 will be reduced sufficiently to meet the NAAQS. The key components of the Libby attainment plan are described as follows:

1. Ambient air quality monitoring in the Libby are a began in 1999 and is conducted using Federal Reference Method (FRM) PM 2.5 samplers at the Courthouse Annex site in downtown Libby. Based on monitoring data from the years 200 1 to 2003, the 3-year annual design value was 15.9 μg/m 3 , which is a violation of the annual PM 2.5 NAAQS. In February 2002, speciation monitoring was conducted to determine possible PM 2.5 emission sources. The results identified

2 The boundaries of the District are identical to th ose for the nonattainment area.15 of 52

organic carbon as the main component of wintertime PM 2.5 emissions. Further ambient monitoring was conducted from November 2003 to Febr uary 2004 to determine the geographic distribution of PM 2.5 concentrations. After additional monitoring from v arious locations beyond Libby city limits and meteorological data from Libb y Courthouse Annex site, it was determined that the Libby Courthouse Annex site represented th e worst-case ambient PM 2.5 levels in the

area. 2. A chemical mass balance study (CMB) was conduct ed during the winter of 2003-2004 by the University of Montana, Center for Environmental Hea lth Sciences (UM-CEHS). The goal of the CMB study was to identify those emission sources in the Libby area that contributed to elevated
PM 2.5 concentrations. The CMB model runs indicated that emissions from residential wood combustion were the major source of the fine partic les on the PM 2.5 filters, averaging 82% during the CMB study period (i.e. winter months). Other c ontributing PM 2.5 sources identified by the CMB model were automobile exhaust (7%), ammonium ni trate (5%), diesel exhaust (4%), and sulfate (2%). 3

3. Carbon 14 ( 14 C) analysis, as a part of the CMB study completed b y UM-CEHS, was conducted by the University of Arizona’s Accelerato r Mass Spectrometry Laboratory Facility to provide further evidence that wood combustion was t he major source of PM 2.5 emissions in Libby. 4

3 Ward, T.J., Rinehart, L.R., Lange, T. The 2003/200 4 Libby, Montana PM 2.5 Source Apportionment Research Study. Aerosol Science and T echnology. Vol. 40:166-177. 2006. 4 Ibid.16 of 52

4. The Libby base year PM 2.5 EI included a quantification of actual PM 2.5 emissions and apportioned the emissions on a seasonal and annual basis for point and area sources. The State used calendar year 2005 as the base year for the de velopment of an EI for the Libby area. The EI was used to support a proportional rollback model f or the emission control plan. The State developed information for 2005 that allowed for the calculation of residential wood combustion and commercial fuel use.

5. The Libby PM 10 SIP as revised also serves as the control plan for emissions of PM 2.5 . Controls exist for reducing emissions from re-entra ined road dust through aggressive street sweeping and flushing, and traction sand durability requirements. Emissions of organic carbon are controlled through residential woodstove regula tions and outdoor burning restrictions.

6. A significant part of the PM 2.5 control strategies has been the completion of a woo dstove changeout program. Approximately 1,130 uncertified woodstoves were replaced with EPAcertified woodstoves or pellet fuel burning devices . After the changeout, PM 2.5 emissions have been reduced from approximately 138.78 tons/year to 57.21 tons/year, a decrease of 59%.
PM 2.5 control strategies are primarily focused on residen tial wood combustion. The control strategies also include: air pollution alerts may b e declared during the winter months; solid fuel burning devices must have an operating permit; only EPA-certified woodstoves and pellet fuel burning devices can obtain permits; and only permit ted pellet fuel devices can operate during air pollution alerts. Other control strategies for PM 2.5 have included an expanded area for the prescribed burning control program and the continui ng federal tailpipe standards.17 of 52

7. Analysis for RACT/RACM was conducted for the Li bby area. EPA’s RACT/RACM guidance covers three general source categories: st ationary, mobile and area (79 FR 20586). The Libby PM 2.5 CMB study did not identify any emissions from loca l stationary sources, only a minor amount from mobile sources, and a significant amount from an area source category – residential wood combustion. EPA’s area source RAC M guidance covers four source categories: (1) reduced solvent usage or solvent substitution; (2) controls on charbroiling or other commercial cooking operations; (3) controls on wood stoves and fireplaces; and (4) new or improved regulations on open burning (79 FR 20586 a nd 20621). The Libby attainment plan concluded that wood combustion control strategies a nd more stringent rules on open burning constituted RACM for area sources. The analysis fu rther noted that the other two categories of area sources, commercial users of solvent and comme rcial cooking, were infrequent in the Libby area. The analysis also considered mobile sources, but determined that in light of their small contribution to PM 2.5 nonattainment, existing federal tailpipe standards and natural turnover rates of the local vehicle fleet made additional measures for mobile sources unnecessary.

8. The Lincoln County Air Pollution Control Progra m is legally enforceable by Lincoln County, and by the State should Lincoln County fail to admi nister the program. The Libby attainment plan also provides for contingency measures if the NAAQS are exceeded after implementation. There is one contingency measure for wood burning f or space heating purposes if it is determined that wood burning emissions contribute t o an exceedance of the PM 2.5 NAAQS, then only biomass pellet fuel burners may operate within the District. Other contingency measures are included for re-entrained dust and industrial f acilities. There is also a review process to consider permanent adoption of a contingency measur e.18 of 52

V. EPA's Analysis of Montana’s Submittal
A. PM 10 SIP Revisions to Lincoln County Air Pollution Cont rol Program EPA’s summary of the PM 10 SIP revisions is addressed in detail under section IV. B. These revisions were made for two purposes: (1) to address PM 2.5 attainment plan requirements; and (2) to improve and strengthen requirements for continued attainment of PM 10 . The revisions are a significant improvement to a plan that was ap proved by EPA 16 years ago. The Libby area has not had an exceedance of the PM 10 NAAQS since 1993. Furthermore, clarifications wer e made to the language to better explain to the publi c the requirements of the air quality program. The revisions removed exemptions and replaced them with requirements for obtaining permits for wood burning appliances. These revisions also added enforcement provisions where previously none had existed.

Section 110(l) of the Clean Air Act states that a SIP revision cannot be approved if the revision would interfere with any applicable requir ement concerning attainment and reasonable further progress toward attainment of the NAAQS or any other applicable requirement of the Act. The Libby area is currently meeting the NAAQS for all criteria pollutants and has not had any violations of the PM 10 standard for over a decade. Furthermore, the revis ions do not relax the stringency of any SIP provision; in fact, the r evisions generally strengthen the SIP. As a result, the PM 10 SIP revisions do not interfere with attainment of the NAAQS or any other applicable requirement of the Act. Therefore, sect ion 110(l) requirements are satisfied.

B. Attainment Demonstration19 of 52

In accordance with section 172(c) of the CAA and t he implementation rule, the attainment plan submitted by Montana for the Libby area included: (1) emission inventories for the plan’s base year (2005) and projection year (20 09); and (2) an attainment demonstration consisting of: (a) technical analyses that locate, identify, and quantify sources of emissions contributing to violations of the annual PM 2.5 NAAQS; (b) analyses of future-year emission reductions and air quality improvements expected to result from national and local programs, and from new measures to meet RACT/ RACM requirements; (c) adopted emission reduction measures; and (d) contingency measures.

C. Analysis of Montana’s submittals 1. Pollutants Addressed and Attainment Date In accordance with policies described in the imple mentation rule, Montana’s PM 2.5 attainment plan evaluates emissions of direct PM 2.5 , SO 2 and NO x in the Libby area. Montana provided documentation of expeditious attainment of the annual PM 2.5 NAAQS in the Libby area by April 2010. Areas that demonstrate attainment b y 2010 are considered to have satisfied the requirement to show reasonable further progress tow ard attainment and need not submit a separate RFP plan. For similar reasons such areas are also not subject to a requirement for a mid-course review.

Montana’s evaluation of emissions is based on the work conducted by UM-CEHS for the CMB model runs indicating that emissions from resid ential wood combustion were the major source (82%) of the fine particles on the PM 2.5 filters. Other PM 2.5 sources identified by the CMB model were automobile exhaust (7%), ammonium ni trate (5%), diesel exhaust (4%), and20 of 52

sulfate (2%). In addition, a Carbon 14 analysis confirmed that wo od combustion is the major source of PM 2.5 emissions in the Libby area and that emissions of b oth SO 2 and NO x are very minor compared to PM 2.5 emissions from residential wood combustion. As des cribed in the emissions inventory, the sources of SO 2 are from home heating oil and sources of NO x are from on-road and off-road mobile sources (see further di scussion in section V.C.7. on NO x emissions from mobile sources).

2. Monitoring Data As shown in the table below, the annual weighted a verage for 2009 shows that the Libby area has met the April 2010 deadline for the 1997 P M 2.5 NAAQS. The trend in annual average concentrations is downward and coincides with the i mplementation of the woodstove changeout program. This is based on quality-controlled and quality-assured monitoring d ata from 2005- 2009 that is available in the EPA Air Quality Syste m (AQS). Table V.2.-1

Year Annual Weighted Average

( μ g/m 3 ) 2005 15.8 2006 15.2 2007 13.0 2008 12.9 2009 10.7
3. Emission Inventory CAA section 172(c)(3) states that for nonattainmen t areas, the State shall prepare a statewide emission inventory no later than three ye ars after designation. The baseline emission inventory for calendar year 2005 or another suitable year shall be used for attainme nt planning (40 CFR 51.1008(b)). EPA promulgated the Air Emiss ions Reporting Rule (AERR) (40 CFR21 of 52

part 51, subpart A) in order to consolidate the var ious reporting requirements that already exist, including those requirements outlined in the PM 2.5 implementation rule. The AERR requires states to report state-wide emissions every three y ears. Montana prepared a statewide emission inventory for 2005. This inventory included annual totals of emissions of criteria pol lutants and their precursors. The State used data from this st atewide inventory to create an emission inventory specific to the Libby area.

Monitoring data for 2005 showed an exceedance of th e PM 2.5 annual standard. The year 2005 is a suitable year for attainment planning bec ause an emission inventory for this year is representative of ambient emission levels that led to the exceedance of the annual standard. The 2005 emission inventory showed that residential woo d burning comprised 82% of the direct
PM 2.5 emissions during the winter. The next largest dire ct source, road dust, was 11%, followed by locomotive emissions at 3.4%. The remaining cri teria pollutant emissions were very minor, including the precursors of PM 2.5 ( i.e. NO x and SO 2 ). Background values of PM 2.5 were accounted for by the State using monitored data col lected at remote stations far away from emissions sources in the Libby area. EPA notes tha t the State used a conservative emission inventory approach for projecting future growth for the 2010 attainment year which involved increasing the vehicle emissions by 2.1% (the popul ation growth rate) from the 2005 base year inventory, and not taking any credit for potential emission reductions that may have been available from fleet turnover and the Federal tailp ipe standards for vehicles. Condensable particulate matter was not considered in the emissi on inventory because of a lack of sources in the Libby area.22 of 52

4. Modeling CAA Section 172(c) requires states with nonattainme nt areas to submit an attainment demonstration. A PM 2.5 attainment demonstration consists of (1) analyses which estimate whether selected emissions reductions will result i n ambient concentrations that meet the NAAQS and (2) a set of control measures which will result in the required emissions reductions.

Montana’s analysis of future-year emissions reduct ions and air quality improvements was based on a proportional rollback model for showing attainment of the standard and a roll forward model demonstrating attainment in the future. The proportional models were applied in conjunction with the findings from chemical mass ba lance and Carbon 14 studies conducted by the University of Montana.

In the particular case of Libby, a proportional mo del is more appropriate than dispersion models. The great majority of periods with elevate d PM 2.5 concentrations in Libby occur during wintertime stagnation conditions. Furthermore, dis persion in Libby is constrained by steep terrain. The most suitable approach for stagnation conditions should be determined on a caseby-case basis, (see sections 7.2.8 and 8.3.4.2(b) o f the Guideline on Air Quality Models, 40 CFR part 51, appendix W), and an alternative model shou ld be selected by the EPA Regional Office when a preferred model is less appropriate (see sec tion 3.2.2 of the Guideline).

The proportional model used the emission inventory for 2005 when there was an exceedance of the standard. The decrease in PM 2.5 emissions for the Libby area resulting from the woodstove changeout program was calculated base d on the amount of wood burned by the23 of 52

EPA-certified woodstoves and then compared to the a mount of emissions resulting from burning the same amount of wood from the uncertified woodst oves that were still in use. The decrease in emissions would be an indication of the effectivene ss of the control strategy. Montana estimated that PM 2.5 emissions would be reduced by 81.57 tons as a resul t of the new EPA-certified woodstoves installed in Libby households.

The State projected future annual average PM 2.5 concentrations for Libby at 9.5 μ g/m 3

. This projection was based on the installation of th e new stoves and a 100 percent compliance with the wood burning restrictions for Libby. EPA’ s guidance is based on emission sources complying with state and local restrictions on emis sion sources (Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations, appendix B, EPA-454/R-05-001, August 2005.) The guidance defines rule effectiveness (RE) as a metho d to account for the reality that not all emission sources are in compliance 100% of the time

.

The guidance provides a listing of the factors tha t are most likely to affect RE. EPA used a conservative 70% RE instead of a 100 percent compliance to determine if Libby would still reach attainment of the PM 2.5 standard. EPA estimated that using the more conse rvative compliance percentage for wood burning restrictions , the future value for Libby would still be below the PM 2.5 standard of 15 μg/m 3

. As stated above in Table V.2.-1 the Libby area 2009 annual average is currently 10.7 μg/m 3

.

5. RACT/RACM24 of 52

Determination of RACT/RACM is a three-step process : (1) identifying potential measures that are reasonable; (2) modeling to ident ify the attainment date that is as expeditious as practicable; and (3) selecting RACT/RACM. Ident ification of potential measures should ordinarily be supported by an inventory of emission s of directly emitted PM 2.5 and of precursors from the relevant sources and source categories; th e technologically feasible control measures for each source or source category; and, for each measu re, the control efficiency, possible emission reductions by pollutant, estimated cost per ton, an d the date by which the measure was or could be implemented; and other relevant information.

For the first step, identification of potential me asures that are reasonable, Montana supported its RACT/RACM analysis with the emissions inventory and the CMB study. The RACT/RACM analysis first noted that there are no ma jor stationary sources of PM 2.5 in the Libby area. It also noted that minor stationary so urces are currently regulated under Montana’s minor source program, which requires permits and a Best Available Control Technology (BACT) review. As discussed in the implementation rule, if state or federal rules already regulate a given sector, it is reasonable for a sta te to look to unregulated sectors for RACT/RACM measures. Furthermore, the implementatio n rule permits the state to use reason in the extent of its effort to identify potential cont rol measures. For example, the rigor of the analysis may depend on the relative contribution of a particular pollutant to the PM 2.5 nonattainment problem (72 FR 20613). As shown by t he CMB study, stationary sources are a very minor contributor to PM 2.5 nonattainment in Libby. Similarly, the RACT/RACM analysis reasoned that mobile sources are currently regulate d, make only a minor contribution to the25 of 52

nonattainment problem, and the overall emissions wi ll continue to be reduced through fleet turnover. Thus, the first step focused on measures for area sources.

The analysis further noted that two types of area sources (commercial users of solvents and commercial charbroilers or other commercial coo king operations) were infrequent in the Libby area. The analysis also discussed re-entrain ed road dust, which the CMB study did not identify as a contributor to PM 2.5 nonattainment, and noted that there were existing SIP provisions to control road dust. As to home heatin g oil, a source of SO 2 , the CMB study found only a 2% contribution to PM 2.5 nonattainment for all sulfates combined. Thus, th e RACM analyses focused on the remaining area sources of w ood burning devices and open burning and identified several control measures to be included in the attainment plan.

For the second step, as discussed in more detail i n section V.C.4, Montana modeled attainment by 2010 based on adoption of these reaso nable control measures. Finally, for the third step, based on the analysis, Montana selected and adopted RACM for wood burning devices and open burning. For wood burning devices , the State developed and implemented a woodstove changeout control strategy. The woodstov e changeout permanently removed 1,130 old, uncertified woodstoves and replaced them with EPA-certified woodstoves or pellet stoves. Additionally, the State adopted measures that requi re permits for solid fuel burning devices (including woodstoves) and restrict installation an d operation of these devices to three categories: pellet stoves, devices with a catalytic emissions control system, and devices with a non-catalytic emissions control system. For the la tter two, emission limits are imposed.26 of 52

RACM measures were also included for major open bur ning, management burning, residential burning, and special burning. The PM 2.5 attainment plan includes BACT and permits for an expanded area, which is the entire Air Pollu tion Control District, for all of these different types of burning activities. Additionally, these b urning activities were restricted to shorter time periods.

In summary, the State evaluated, by source categor y, sources of direct PM 2.5 , SO 2 and
NO x for RACT/RACM control measures. The State’s evalua tion of sources of SO 2 and NO x resulted in their decision that no additional contr ols are necessary to attain the NAAQS based on the absence of major sources or area sources that c an be cost effectively or reasonably controlled. The State therefore adopted RACM for direct PM 2.5 . In accordance with Section 172(c) of the CAA, Montana has adopted all RACT/RACM needed to at tain the standards as expeditiously as practicable. EPA has reviewed Montana’s RACT/RACM analysis and has determined that the state reasonably identified potential control measu res, modeled the attainment date that is as expeditious as practicable and reasonably selected RACT/ RACM for the Libby area.

6. Contingency Measures In conformance with Section 172(c)(9) of the CAA, the implementation rule requires that
PM 2.5 attainment area plans include contingency measures . These measures must be fully adopted or otherwise ready for quick implementation , should contain trigger mechanisms and an implementation schedule, should be measures not inc luded in the SIP control strategy, and should provide the equivalent of one year of RFP. Once triggered, a contingency measure should take effect without further action by the St ate or EPA.27 of 52

The Libby SIP contains contingency measures for re sidential wood burning, re-entrained dust, and industrial facilities. If it is determin ed that residential wood burning contributes to an exceedance of the PM 2.5 NAAQS, then only biomass pellet fuel burners may op erate within the District. If re-entrained dust contributes to nonc ompliance, then the existing regulations (which currently only apply in a limited area) are made ap plicable to the entire Air Pollution Control District. Finally, if an industrial facility contr ibutes to noncompliance, the Montana Department of Environmental Quality (MTDEQ) will initiate cont ingency measures to reduce emissions. Once a contingency measure is initiated, it must re main active until the Libby SIP demonstration is revised and resubmitted to EPA for approval.

The contingency measures for residential wood burn ing and re-entrained dust meet the requirements of the implementation rule. The conti ngency measure for major point sources would require further action by MTDEQ to determine whether additional controls are necessary. However, the contingency measures for residential w ood burning and re-entrained dust are sufficient to meet the requirements of the CAA, inc luding equivalence to one year of RFP.

7

. Transportation Conformity Requirements Transportation conformity is required under CAA sec tion 176(c) (42 U.S.C. 7506(c)) to ensure that transportation plans, transportation im provement programs (TIPs) and federally supported highway and transit projects are consiste nt with (“conform to”) the state air quality implementation plan. Transportation conformity app lies to areas that are designated nonattainment, and to those areas redesignated to a ttainment after 1990 with a CAA section28 of 52

175A maintenance plan (“maintenance areas”), for tr ansportation-related criteria pollutants: carbon monoxide (CO), NO x and particulate matter (PM 2.5 and PM 10 ).

EPA’s transportation conformity rule (40 CFR parts 51 and 93) establishes the criteria and procedures for determining whether transportati on activities conform to the SIP. One requirement of the rule is that transportation plan s, TIPs, and projects must satisfy a regional emissions analysis for the relevant pollutants and precursors (40 CFR 93.118, 119). However, section 93.109(m) of this rule states that an area is not required to satisfy a regional emissions analysis for a pollutant or precursor if the SIP de monstrates that motor vehicle emissions of that pollutant or precursor are an insignificant contrib utor to the area’s air quality problem. In today’s notice, EPA is proposing to find that motor vehicle emissions of PM 2.5 and NO x are insignificant contributors to Libby’s PM 2.5 nonattainment problem. If this proposal is finali zed,
PM 2.5 and NO x motor vehicle emissions budgets (MVEB) would not b e established and a regional emissions analysis would not be required f or either PM 2.5 or NO x in any future conformity determination in Libby. Please note, ho wever, that this proposed action would not apply to PM 2.5 hot-spot analyses for individual projects, if such an analysis is required in the future for transportation conformity purposes.

There are specific transportation conformity provi sions that EPA proposes to determine as applicable to the Libby PM 2.5 nonattainment area. As provided in more detail in 40 CFR 93.109(m), these specific conformity provisions are addressed when EPA finds that emissions from motor vehicles in the Libby PM 2.5 nonattainment area are an insignificant contributo r to the areas’ nonattainment problem for a relevant NAAQS a nd/or precursor.29 of 52

To consider making such an insignificance finding, EPA evaluated the provisions of 40 CFR 93.109(m) against the relevant information cont ained in the SIP attainment plan, the SIP revision’s associated technical support document (T SD), and additional information as developed by EPA. We evaluated the following facto rs in determining whether on-road direct
PM 2.5 and NO x emissions are insignificant contributors to the are a’s PM 2.5 air quality problem; (1) the percentage of motor vehicle emissions in th e context of the total SIP inventory; (2) the current state of air quality as determined by monit oring data for that NAAQS; (3) the absence of SIP motor vehicle control measures; and (4) histori cal trends and future projections of the growth of motor vehicle emissions. Our evaluation and con clusions are as follows:

a. The percentage of PM 2.5 motor vehicle emissions in the context of the tota l SIP inventory. This factor, with regard to PM 2.5 emissions, is addressed in two areas of the SIP re vision documentation. Table 27.12.11.4B (“PM 2.5 Annual Demonstration of Compliance”) of the Libby attainment plan provides relevant information with regard to 2003-2004 CMB percentages by source category, percent reduction i n emissions due to control strategies, estimated growth in emissions over the 2005 to 2010 time period, and 2010 compliance year contributions. The dominant CMB source was residen tial woodstoves at 82% with motor vehicle tailpipe emissions at 7% of total PM 2.5 mass and diesel exhaust at 4% of the total PM 2.5

mass.30 of 52

The contribution of motor vehicle PM 2.5 emissions is also documented in Table 5.1A

(“Seasonal PM 2.5 Emissions in Libby by Source Cate gory”) of the SIP’s TSD. Table 5.1A presents estimated emissions based on metric tons a nd percentage of the inventory for 2005, by season; we have provided these motor vehicle tailpi pe PM 2.5 emissions, as percent of total PM 2.5 emissions, in Table V.7-1 below. We note that in Table 5.1A of the SIP’s TSD, the inventory is dominated by woodstove emissions in all four sea sons.

Table V.7.-1 Motor Vehicle PM 2.5 Emissions Percentage of Total Inventory for 2005 (all figures are in metric tons) Season Motor Vehicle PM 2.5

Emissions Total Inventory PM 2.5

Emissions Motor Vehicle

Emissions % of Total Winter 0.48 80.63 0.59 Spring 0.55 46.43 1.18 Summer 0.66 13.66 4.83 Fall 0.51 97.67 0.52 Total Year 2.2 238.38 0.92

As shown in Table V.7.-1 above, motor vehicle ta ilpipe PM 2.5 emissions represent an

annual average of only 0.92 % of the total PM 2.5 inventory. That is, motor vehicle emissions are less than one percent of the inventory over the cou rse of a year. During the summer, motor vehicle emissions make up close to five percent of the inventory, but motor vehicle emissions are only slightly higher during the summer than during other seasons. The motor vehicle emissions percentage is much greater during the summer compar ed with other seasons primarily because total PM 2.5 emissions are significantly reduced during the sum mer compared to other seasons; summer is the season with the fewest emissions from woodstoves. The information provided in the State’s submittal supports a conclusion that re gional PM 2.5 on-road mobile source emissions are a minimal percentage in the context of the tota l PM 2.5 emissions inventory. Therefore, this31 of 52

factor supports the proposed finding that on-road P M 2.5 emissions are insignificant for the Libby
PM 2.5 nonattainment area.

b. The current state of air quality as determined by monitoring data for the PM 2.5 NAAQS. This factor is addressed as shown in the table bel ow. From the State’s SIP revision and section V.B.2 above, from 2007 to 2009 the Libby ar ea continues to demonstrate attainment of the 1997 annual PM 2.5 NAAQS. Furthermore, the trend in annual average c oncentrations is downward and coincides with the implementation of t he woodstove changeout program. This data is based on quality-controlled and quality-ass ured monitoring data from 2005-2009 that are available in the EPA AQS. This factor supports the proposed finding that on-road PM 2.5 emissions are insignificant for the Libby PM 2.5 nonattainment area.

Table V.2.-1

Year PM 2.5 Annual Weighted

Average ( μ g/m3) 2005 15.8 2006 15.2 2007 13.0 2008 12.9 2009 10.7

c. The absence of SIP motor vehicle co ntrol measures for PM 2.5 .32 of 52

The Libby PM 2.5 attainment plan relies on a 59% reduction in resid ential woodstove emissions to reach attainment of the annual PM 2.5 NAAQS and took no credit for any emission reductions in the motor vehicle tailpipe and diesel exhaust categories (e.g. Federal tailpipe emission standards and fleet turnover). The State further described these assumptions in sections 27.12.7.3 (“Federal Tailpipe Standards Con trol Program”) and 27.12.11.4 (“PM 2.5 2010 Demonstration of Compliance”) of the Libby attainme nt plan. EPA also notes there is no State or local mandated motor vehicle emission control re quirements (e.g., inspection and maintenance program, fuels, or transportation contr ol measures) for the Libby PM 2.5 nonattainment area. Therefore, this factor support s the proposed finding that on-road PM 2.5 emissions are insignificant for the Libby PM 2.5 nonattainment area.

d. Historical trends and future projecti ons of the growth of motor vehicle PM 2.5 emissions. Libby’s annual PM 2.5 2001–2003 design value was 15.9 μg/m 3 . In November 2003 through February 2004 air quality data was collecte d in Libby to support CMB modeling. This CMB modeling showed that residential wood smoke was the primary source of PM 2.5 in Libby. Table 27.12.11.4B in the Libby attainment plan show s that, when the results of the CMB modeling are applied to the air quality data from 2 001-2003, residential wood smoke contributed 13.0 μg/m 3 (82%) of the 2001–2003 annual PM 2.5 design value, motor vehicle tailpipe emissions contributed 1.1 μg/m 3 (7%), and diesel exhaust emissions contributed 0.7 μg/m 3 μg/m 3 (4%). Based on the results of this modeling Montana based its attainment strategy for the area on a woodstove change-out program.33 of 52

The SIP assumes that the woodstove change-out prog ram will reduce those emissions by 59% in 2010. The SIP also assumes that motor vehic le tailpipe emissions and diesel exhaust emissions would grow by 2.1% between 2005 and 2010, which is equal to the expected population growth rate during that period. The SIP does not account for any reductions in motor vehicle emissions or diesel exhaust that would occu r due to fleet turnover to new lower emission motor vehicles, on-road diesel vehicles or off-road equipment. Table 27.12.11.4B in the Libby attainment plan shows that in 2010 the predicted an nual average PM 2.5 concentration would be 8.37 μg/m 3 . The table also shows that residential wood smoke is expected to contribute 5.44 μg/m 3 (65%) in 2010, motor vehicle tailpipe emissions wo uld contribute 1.12 μg/m 3 (13%), and diesel exhaust emissions would contribute 0.71 μg/m 3 (8%). As can be seen, on a percentage basis the contribution of motor vehicle emissions a nd diesel exhaust increases; however, overall
PM 2.5 concentrations are expected to decrease by 53% to 8 .37 μg/m 3 , the contribution of wood smoke emissions is expected to decrease by 59%, and the total contribution of emissions from motor vehicles and diesel exhaust to PM 2.5 mass in 2010 is expected to increase by only 0.03 μg/m 3 between 2005 and 2010. This increase in mass is d ue to the assumptions that emissions from these sources increase at the same rate as pop ulation growth and that no emissions reductions from fleet turnover are included in the calculations. Both of these are conservative assumptions.

EPA notes that the contribution of motor vehicle emissions of 13% to PM 2.5 mass in 2010 represents the projected chemical mass balance of P M 2.5 and not an emission inventory projection. The SIP includes a base year PM 2.5 inventory (Table 5.1A) for 2005. That inventory shows that motor vehicle emissions of PM 2.5 are 2.20 tpy and that total PM 2.5 emissions in the34 of 52

base year are 238.39 tpy. Therefore, the motor veh icle emissions in the base year are slightly less than 1% of the total direct PM 2.5 emissions. On the surface this may seem to be in c onflict with the results of the CMB modeling, which shows t hat motor vehicle exhaust contributed about 7% of the PM 2.5 mass in the base year. However, it should be note d that the chemical mass balance data and the PM 2.5 data collected at the Libby Courthouse Annex repre sents only one receptor within the City of Libby, and only for the period of late 2003 through early 2004. While this location is believed to be representative of L ibby's air quality, numerous factors influence the local particulate matter concentrations and air quality. Local scale meteorology (wind speed, wind direction, temperature, relative humidity, bar ometric pressure, and solar radiation at a minimum), traffic patterns, and precipitation are a few examples of these factors which vary throughout the city. Accepting that variable condi tions exist throughout Libby, as well as the inherent uncertainty associated with ambient air mo nitoring, the difference that exists between
PM 2.5 monitoring data at one receptor and a city-wide em ission inventory appears to be plausible.

We also note that the actual location of the monit or may have exposed it to additional influence from motor vehicle emissions. We have no t performed an in-depth analysis, but we do note that the monitor is located directly adjacent to U.S. Highway 2, the main north/south highway through Libby. Although motor vehicle PM 2.5 emissions are shown to be minimal in the State’s emissions inventory (ref. Table 5.1A: "Seasonal PM 2.5 Emissions in Libby by Source Category" and Table V.7.-1 above), motor vehicle em issions may have shown a greater than anticipated contribution on the chemical mass balan ce analysis due to the monitor's close proximity to Highway 2.35 of 52

Overall, this factor supports the proposed finding that on-road PM 2.5 emissions are insignificant for the Libby PM 2.5 nonattainment area. In summary, all four factors support the proposed finding. After weighing these four factor s described in 40 CFR 93.109(m) and evaluated above, EPA proposes to find that on-road PM 2.5 emissions are insignificant for the Libby PM 2.5 nonattainment area. We turn to applying the four factors to on-road NO x emissions.

e. The percentage of NO x motor vehicle emissions in the context of the tota l SIP inventory. The Libby attainment plan focuses on directly emit ted PM 2.5 and controls of PM 2.5 emissions from woodstoves and does not address any motor vehicle NO x emissions other than to indicate in Table 27.12.11.4B "PM 2.5 Annual Demonstration of Compliance" that the CMB d ata show that ammonium nitrate was only 5% of the mass found on the filters. EPA, therefore, drew upon other relevant, available data to evaluate whe ther NO x motor vehicle emissions in the Libby PM 2.5 nonattainment area are significant and require tha t a NO x motor vehicle emissions budget be established for transportation conformity purposes or whether on-road NO x emissions could be found insignificant based on the criteria in 40 CFR 93.109(m).

EPA reviewed relevant information from EPA's Natio nal Emissions Inventory (NEI) data for 2005 that were used for the 2009 final designat ions for the 24-hour 2006 PM 2.5 NAAQS (74 FR 58688, November 13, 2009). 5 However, since the NEI data were for Lincoln Coun ty as a whole, we needed to assess how much of the Lincoln County on-road NO x inventory could be36 of 52

apportioned to the Libby PM 2.5 nonattainment area. Our methodology was to calcul ate how many vehicle miles traveled (VMT) the Libby PM 2.5 nonattainment area contributes to Lincoln County’s total VMT and to assign that same proporti on of the total Lincoln County on-road NO x emissions to the Libby PM 2.5 nonattainment area, as explained further below. W e then needed to determine what percentage this was of total NO x from the Libby PM 2.5 nonattainment area.

Specific emissions data for Lincoln County, MT, w hich includes the Libby PM 2.5 nonattainment area, are presented in Table V.7.-2 b elow and are from EPA’s PM 2.5 24-hour 2006 NAAQS final designations information.

Table V.7.-2 (All emission figures are in tons per year) County Major

Category VOC NO x SO2 NH3 PM2.5 OC EC SO4 NO3 PMFine
Lincoln Fires 6106 310 277 425 2199 1286 219 20 10 664 Lincoln NonRoad 338 2403 169 1 76 16 55 0 0 4
Lincoln On-Road 366 545 15 23 11 3 6 0 0 2 Lincoln OtherStationary 871 138 74 57 453 108 16 5 1 323
Total 7681 3395 535 506 2738 1412 296 25 11 994

The "On-Road" or motor vehicle, 2005 NEI emissions were calculated by EPA for Lincoln County based on a county annual total of VM T of 231,246,800. This VMT figure,

5 The 2005 NEI data from EPA's PM 2.5 24-hour 2006 NAAQS final designations information are available at: http://www.epa.gov/ttn/naaqs/pm/pm25_ 2006_techinfo.html

.37 of 52

which represents data for the entire county, is als o referenced in our 2006 PM 2.5 24-hour NAAQS final designations information. 6

Based on the 2005 NEI data referenced above in Tabl e V.7.-2, Lincoln County’s total annual VMT of 231,246,800 results in approximately 545 tpy of on-road NO x . To calculate the estimated on-road NO x emissions for the Libby PM 2.5 nonattainment area, we first needed to determine what percentage of Lincoln County’s total VMT is attributed to the Libby PM 2.5 nonattainment area. We then applied that VMT perce ntage to the total Lincoln County on-road
NO x emissions to get the estimated on-road NO x emissions for the Libby PM 2.5 nonattainment area. The total VMT for the Libby PM 2.5 nonattainment area, 54,877,360, came from the MTDEQ. 7 This is 23.73% of Lincoln County’s total VMT (i.e ., 54,877,360 VMT from Libby divided by 231,246,800 VMT from Lincoln County as a whole). It is reasonable to assume that the Libby PM 2.5 nonattainment area contributes this same percentag e of on-road NO x emissions to the total Lincoln County on-road NO x emissions. Therefore, we applied this 23.73% to t he Lincoln County total of 545 tpy of on-road motor ve hicle NO x emissions, which results in approximately 129.33 tpy of on-road NO x emissions for the Libby PM 2.5 nonattainment area. In lieu of other specific data, EPA considers this app roach a reasonable estimate of the on-road NO x emissions for the Libby PM 2.5 nonattainment area.

Once we had a figure for the number of tons of on- road NO x emissions from Libby, the next step in our analysis was to determine what per centage of the total anthropogenic NO x this

6 See http://www.epa.gov/ttn/naaqs/pm/pm25_2006_tech info.html; Factor 4.B "Vehicle Miles Traveled".38 of 52

represents. Again, since the NEI data available we re for Lincoln County as a whole, we needed to assess how much of the Lincoln County total anth ropogenic NO x could be apportioned to the Libby PM 2.5 nonattainment area. To do so, we needed to establ ish what NO x emissions were from anthropogenic sources in the Libby PM 2.5 nonattainment area other than from on-road motor vehicle tailpipes. To develop these particul ar emissions figures, we assumed that the percentage of Lincoln County’s anthropogenic NO x coming from Libby would be the same as the percentage of Lincoln County’s anthropogenic PM 2.5 emissions coming from Libby, as described below.

First, we determined the anthropogenic NO x emissions for Lincoln County from the “Non-Road” and “Other Stationary” source categories . We used the data from Table V.7.-2 above and eliminated the "Fires" 8 and "On-Road" emissions categories from the Lincol n County 2005 NEI data (see Table V.7.-3 below):

Table V.7.-3 (All emissions are in tons per year) County Major

Category VOC NO x SO2 NH3 PM2.5 OC EC SO4 NO3 PM Fine Lincoln NonRoad 338 2403 169 1 76 16 55 0 0 4
Lincoln OtherStationary 871 138 74 57 453 108 16 5 1 323 Total 1209 2541 243 58 529 124 71 5 1 327
The total anthropogenic NO x in Lincoln County from sources other than on-road is 2541 tpy.

7 VMT data was communicated in a February 26, 2010, email from Jim Carlin of MTDEQ to Tim Russ of EPA Region 8.39 of 52

Next, we summed-up the PM 2.5 emissions from the Libby PM 2.5 nonattainment area from the State's SIP emission inventory Table 5.1A, but did not include emissions from fires (i.e.,
PM 2.5 emissions from "Large Prescribed Burning" and "Gen eral Burning" were not included from the State's Table 5.1A); see Table V.7.-4 belo w.

Table V.7.-4: Libby Anthropogenic PM 2.5 Emissions (As adapted from Table 5.1A “Seasonal PM 2.5 Emissions in Libby by Source Category” of the Libby Attainment SIP Emission Inventory) Sources Winter Spring Summer Fall Woodstoves Residential/Com. 66.65 20.74 5.08 58.76
Paved Roads Fugitive Dust 8.92 2.57 3.23 9.61 Large Prescribed Burning - - - - - - - - - - - - General Burning - - - - - - - - - - - - Locomotives 2.72 2.72 2.72 2.72 Unpaved Roads Fugitive Dust 1.22 1.34 1.53 1.2 Propane Heating Residential/Com. 0.13 0.04 0.01 0.11 Oil Heating Residential/Com. 0.48 0.15 0.04 0.42
Aircraft 0.0 0.03 0.03 0.0 Road & Building Construction Dust 0.02 0.36 0.36 0.36
Motor Vehicle Tailpipe 0.48 0.55 0.66 0.51 Total (Metric Tons) 80.62 28.50 13.66 73.69
Total Short Tons (2000 lbs. per ton) 88.88 31.42 15.06 81.24 Total Annual Anthropogenic Short Tons of PM 2.5 Emissions = 216.60 tons.

Based on the data in Table V.7.-4 above, the total annual anthropogenic short tons of
PM 2.5 emissions (without including emissions from the “M otor Vehicle Tailpipe” category) from

8 The “Fires” category of the 2005 NEI relates to wi ldfires, prescribed burns and such. This correlates to the “Large Prescribed Burning” and “G eneral Burning” categories in the State’s Table 5.1A.40 of 52

“Non-Road” and “Other Stationary” sources in the Li bby PM 2.5 nonattainment area are estimated as 214.17 tons per year.

The Libby PM 2.5 nonattainment area's annual emissions of PM 2.5 from “Non-Road” and “Other Stationary” anthropogenic sources is 214.17 tpy, whereas these sources emit 529 tpy for Lincoln County as a whole (see Table V.7.-3 above). Therefore, Libby’s share of Lincoln County’s PM 2.5 emissions from “Non-Road” and “Other Stationary” a nthropogenic sources is approximately 40.48%.

We then added Lincoln County NO x emissions from the “Non-Road” and “Other Stationary” sources categories, 2541 tpy (see Table V.7-3 above), and attributed 40.48% of those emissions to the Libby PM 2.5 nonattainment area's NO x “Non-Road” and “Other Stationary” sources categories, which results in 1028.6 tpy. To summarize, EPA estimated the Libby PM 2.5 nonattainment area's on-road NO x motor vehicle emissions as 129.33 tpy, and the non -road and other stationary sources’ NO x emissions as 1028.6 tpy. Therefore, the total est imated annual anthropogenic NO x emissions from all of these source categories are estimated to be 1157.93 tpy for the Libby PM 2.5 nonattainment area. The approximate contribution of annual on-road NO x motor vehicle emissions (129.33 tpy) to the total e stimated NO x annual anthropogenic emissions from all sources (1157.93 tpy) in the Libby PM 2.5 nonattainment area is 11.17% of the total inventory.

EPA indicated in its July 1, 2004 Transportation C onformity final rule (69 FR 40004) that mobile source emissions of approximately 10% m ay be considered insignificant, but did not41 of 52

make 10% a specific threshold. While the 11.7% fig ure calculated for on-road NO x in the Libby
PM 2.5 nonattainment area is slightly greater than this, in this same rulemaking EPA explained: "This example also illustrates the reason EPA belie ves it is important to have flexibility in implementing this provision. Although the comme nter specifically mentions 10% as the threshold for finding motor vehicle emissions i nsignificant, EPA clarifies that this figure is a general guideline only. Depending on t he circumstances, we may find that motor vehicle emissions that make up less than 10% of an area’s total inventory are still significant. Conversely, we may also find that mot or vehicle emissions in excess of 10% are still insignificant, under certain circumstance s relating to the overall composition of the air quality situation. In general, the percent age of motor vehicle emissions in the area’s total inventory is an important criterion fo r determining whether motor vehicles are a significant or insignificant contributor to an ar ea’s air quality problem, yet there are other criteria that EPA will examine when making th is finding, as described in the regulatory text for § 93.109(k).” (69 FR 40062) 9
As stated in the 2004 preamble, 10 percent is a gui deline only. As described below, EPA considered other factors that lead EPA to propose t hat motor vehicle emissions of NO x are an insignificant regional contributor to the PM 2.5 nonattainment problem.

f. The current state of air quality as determined by monitoring data for PM 2.5 NAAQS. This factor is addressed with the ambient PM 2.5 air quality data presented in section V.7.B above which demonstrate the Libby PM 2.5 nonattainment area is attaining the PM 2.5 annual42 of 52

NAAQS. Additional data, relevant to NO x or in this case nitrates derived from NO x emissions, 10 were provided by EPA with the 2009 final designatio ns for the 24-hour 2006 PM 2.5 NAAQS. This information, as provided in Table V.7-5 below, is from EPA's PM 2.5 24-hour 2006 NAAQS final designations and is located at: http://www.epa.gov/ttn/naaqs/pm/pm25_2006_techinfo. html

Table V.7-5: PM 2.5 Composition Data for Libby, MT Area/County/State PM 2.5

Composition Data Sulfate

(μmg/m 3 ) Nitrate

(μmg/m 3 ) Carbon

(μmg/m 3 ) Crustal

(μmg/m 3 ) Total

(μmg/m 3 ) Nitrate

Percent Carbon

Percent Libby/Lincoln/MT Total

Concentration (Cold) 1.4 0.8 41.9 0.3 44.4 2 94

Regional

Concentration (Cold) 0.9 0.4 2.4 0.2 3.9 10 62

Urban

Concentration (Cold) 0.5 0.4 39.5 0.1 40.5 1 98

Total

Concentration (Warm) 1.2 0.0 6.7 0.8 8.7 0 77

Regional

Concentration (Warm) 1.0 0.0 2.5 1.1 4.6 0 54

Urban

Concentration (Warm) 0.2 0.0 4.2 0.0 4.4 0 95

Total

Concentration (Annual Average) 1.0 0.1 12.8 0.4 14.3 1 90

As can be seen in Table V.7-5 above, nitrates (as d erived from NO x ) are a very small component of the PM 2.5 composition found in the Libby PM 2.5 nonattainment area. Therefore,
NO x as derived from motor vehicle tailpipe emissions a lso is a very small component. This

9 EPA redesignated the insignificance provision of t he transportation conformity rule from 40 CFR 93.109(k) to 40 CFR 93.109(m) in its March 24, 2010 “PM Amendments” final rule (75 FR 14260).43 of 52

factor thus supports the proposed finding that on-r oad NO x emissions are insignificant for the Libby PM 2.5 nonattainment area.

g. The absence of SIP motor vehicle control measu res for NO x . As discussed in section V.7.C above, the Libby PM 2.5 attainment plan took no credit for any emission reductions in the motor vehicle tailpi pe and diesel exhaust categories (e.g. Federal tailpipe emission standards and fleet turnover). T he State further described these assumptions in sections 27.12.7.3 (“Federal Tailpipe Standards Con trol Program”) and 27.12.11.4 (“PM 2.5 2010 Demonstration of Compliance”) of the Libby attainme nt plan. EPA also notes there is no State or local mandated motor vehicle emission control re quirements (e.g., inspection and maintenance program, fuels, or transportation control measures) for the Libby PM 2.5 nonattainment area. Therefore this factor supports the proposed finding that on-road NO x emissions are insignificant for the Libby PM 2.5 nonattainment area.

h

. Historical trends and future projections of the gro wth of NO x motor vehicle emissions. As noted in our discussion in section V.7.D above , the Libby attainment plan uses a 59% reduction in residential woodstove emissions to rea ch attainment of the annual PM 2.5 NAAQS and took no credit for any emission reductions in t he motor vehicle tailpipe and diesel exhaust categories. The State further described these assu mptions in sections 27.12.7.3 (“Federal Tailpipe Standards Control Program”) and 27.12.11.4 (“PM 2.5 2010 Demonstration of Compliance”) of the Libby attainment plan. EPA not es that the State used a conservative

10 Nitrogen oxides react in the atmosphere to form ni trates. For our purposes, the impact of44 of 52

emission inventory approach for projecting the 2010 attainment year future growth which involved merely increasing the vehicle emissions by 2.1% (the population growth rate) from the 2005 base year inventory, and not taking any credit for potential emission reductions that may have been available from fleet turnover and the Fed eral tailpipe standards for vehicles. In addition, as we noted above, there are no State or local mandated motor vehicle emission control requirements (e.g., inspection and maintenance prog ram) for the Libby PM 2.5 nonattainment

area.

This factor supports the proposed finding that on -road NO x emissions are insignificant for the Libby PM 2.5 nonattainment area. After weighing these four fac tors described in 40 CFR 93.109(m) and evaluated above, EPA proposes to find that on-road NOx emissions are insignificant for the Libby PM 2.5 nonattainment area.

i. Conclusion. In view of our evaluation presented above per 40 C FR 93.109(m), EPA is proposing to find that direct PM 2.5 and NO x motor vehicle emissions are an insignificant contr ibutor to the air quality issues associated with the PM 2.5 annual NAAQS in the Libby PM 2.5 nonattainment area; thus, motor vehicle emission budgets for on-road di rect PM 2.5 and NO x would not be established by this rulemaking. Based on our evaluation of the four factors described in 93.109(m), EPA proposes to conclude that it would be unreasonable to expect that the Libby PM 2.5 nonattainment area would experience enough motor vehicle emission s growth such that a PM 2.5 annual NAAQS violation would occur.

NOx emissions is measured as the amount of nitrates found at the PM 2.5 monitor.45 of 52

VI. Proposed Action The EPA has reviewed Montana’s SIP revision for att aining the 15μg/m 3 annual PM 2.5 NAAQS for the Libby PM 2.5 nonattainment area. EPA is proposing to approve t he State of Montana’s revisions to the Lincoln County Air Pollu tion Control Program to be included in Montana’s SIP, submitted on June 26, 2006, and the Libby PM 2.5 attainment plan, submitted on March 26, 2008. Action was not taken earlier on th e June 26, 2006, submittal at the request of the State of Montana to delay action until the subm ittal of the Libby PM 2.5 attainment plan at a later date. EPA has determined that the SIP meets applicable requirements of the CAA, as described in the Clean Air Fine Particle Implementa tion Rule. Specifically, EPA has determined that Montana’s SIP includes an attainment demonstra tion and adopted state regulations and programs needed to support the determination that t he Libby PM 2.5 nonattainment area will continue attaining the annual PM 2.5 NAAQS. Finally, EPA is proposing to find on-road, directly emitted PM 2.5 and NO x in the Libby, Montana nonattainment area insignifi cant for regional transportation conformity purposes.

VII

. Statutory and Executive Order Reviews A

. Executive Order 12866, Regulatory Planning and Revi ew Under Executive Order 12866, (58 Federal Register 5 1735 (October 4, 1993)) the Agency must determine whether the regulatory action is "significant" and therefore subject to the Office of Management and Budget (OMB) review and th e requirements of the Executive Order. The Order defines "significant regulatory action" a s one that is likely to result in a rule that may: (1) have an annual effect on the economy of $100 mi llion or more or adversely affect in a material way the economy, a sector of the economy, productivity, competition, jobs, the46 of 52

environment, public health or safety, or state, loc al, or tribal governments or communities; (2) create a serious inconsistency or otherwise interfe re with an action taken or planned by another agency; (3) materially alter the budgetary impact o f entitlements, grants, user fees, or loan programs or the rights and obligations of recipient s thereof; or (4) raise novel legal or policy issues arising out of legal mandates, the President 's priorities, or the principles set forth in the Executive Order." The OMB has exempted this regula tory action from Executive Order 12866 review.

B. Paperwork Reduction Act This action does not impose an information collecti on burden under the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 ET seq . This action proposes to approve the SIP revisions submitted by the State of Montana.

C. Regulatory Flexibility Act The Regulatory Flexibility Act (RFA) generally requ ires an agency to prepare a regulatory flexibility analysis of any rule subject to notice and comment rulemaking requirements under the Administrative Procedure Act or any other statute unless the agency certifies that the rule will not have a significant economic impact on a substantial number of small entities. Small entities include small busin esses, small organizations, and small governmental jurisdictions.

This proposed rule will not have a significant impa ct on a substantial number of small entities because SIP approvals and disapprovals und er section 110 and subchapter I, part D of the47 of 52

Clean Air Act do not create any new requirements, b ut simply approve or disapprove requirements that the state is already imposing. T herefore because the Federal SIP approval does not create any new requirements, I certify that thi s action will not have a significant economic impact on a substantial number of small entities. Moreover, due to the nature of the Federal-state relationship under the Clean Air Act, preparation o f flexibility analysis would constitute Federal inquiry into the economic reasonableness of state a ction. The Clean Air Act forbids EPA to base its actions concerning SIPs on such grounds. Union Electric Co., v. U.S. EPA , 427 U.S. 246, 255-66 (1976); 42 U.S.C. 7410(a)(2).

D. Unfunded Mandates Reform Act Title II of the Unfunded Mandates Reform Act of 199 5 (UMRA), P.L. 104-4, establishes requirements for Federal agencies to assess the eff ects of their regulatory actions on state, local, and tribal governments and the private sector. Und er section 202 of the UMRA, EPA generally must prepare a written statement, including a cost- benefit analysis, for proposed and final rules with "Federal mandates" that may result in expendit ures to state, local, and tribal governments, in the aggregate, or to the private sector, of $100 million or more in any one year. Before promulgating an EPA rule for which a written statem ent is needed, section 205 of the UMRA generally requires EPA to identify and consider a r easonable number of regulatory alternatives and adopt the least costly, most cost-effective or least burdensome alternative that achieves the objectives of the rule. The provisions of section 205 do not apply when they are inconsistent with applicable law. Moreover, section 205 allows EPA to adopt an alternative other than the least costly, most cost-effective or least burdenso me alternative if the Administrator publishes with the final rule an explanation why that alterna tive was not adopted. Before EPA establishes48 of 52

any regulatory requirements that may significantly or uniquely affect small governments, including tribal governments, it must have develope d under section 203 of the UMRA a small government agency plan. The plan must provide for notifying potentially affected small governments, enabling officials of affected small g overnments to have meaningful and timely input in the development of EPA regulatory proposal s with significant Federal intergovernmental mandates, and informing, educating, and advising sm all governments on compliance with the regulatory requirements.

EPA has determined that this rule does not contain a Federal mandate that may result in expenditures of $100 million or more for state, loc al, and tribal governments, in the aggregate, or the private sector in any one year. This Federal a ction proposes to partially approve and partially disapprove pre-existing requirements under state or local law, and to disapprove a redesignation request, and imposes no new requirements. Accordin gly, no additional costs to state, local, or tribal governments, or to the private sector, resul t from this action. Thus, today's rule is not subject to the requirements of sections 202 and 205 of the UMRA.

E. Executive Order 13132, Federalism Executive Order 13132, entitled “Federalism” (64 F R 43255, August 10, 1999), requires EPA to develop an accountable process to ensure “me aningful and timely input by state and local officials in the development of regulatory policies that have federalism implications.” “Policies that have federalism implications” is defined in th e Executive Order to include regulations that have “substantial direct effects on the states, on the relationship between the national government49 of 52

and the states, or on the distribution of power and responsibilities among the various levels of government.”

This proposed rule does not have federalism implications. It wil l not have substantial direct effects on the states, on the relationship b etween the national government and the states, or on the distribution of power and responsibilities a mong the various levels of government, as specified in Executive Order 13132. This rule merely proposes to partially approve and partially disapprove state rules implementing a Federal stand ard, and to disapprove a redesignation request, and does not alter the relationship or the distribution of power and responsibilities established in the Clean Air Act. Thus, Executive Order 13132 does not apply to this rule.

F. Executive Order 13175, Coordination with Indian Tribal Governments Executive Order 13175, entitled Consultation and Co ordination with Indian Tribal Governments (65 FR 67249, November 9, 2000), requir es EPA to develop an accountable process to ensure meaningful and timely input by tr ibal officials in the development of regulatory policies that have tribal implications. This propo sed rule does not have tribal implications, as specified in Executive Order 13175. It will not ha ve substantial direct effects on tribal governments, on the relationship between the Federa l government and Indian tribes, or on the distribution of power and responsibilities between the Federal government and Indian tribes. This action does not involve or impose any requirem ents that affect Indian Tribes. Thus, Executive Order 13175 does not apply to this rule.50 of 52

G. Executive Order 13045, Protection of Children from Environmental Health Risks and Safety Risks Protection of Children from Environmental Health Ri sks and Safety Risks (62 FR 19885, April 23, 1997), applies to any rule that: (1) is d etermined to be economically significant as defined under Executive Order 12866, and (2) concer ns an environmental health or safety risk that EPA has reason to believe may have a dispropor tionate effect on children. If the regulatory action meets both criteria, the Agency must evaluat e the environmental health or safety effects of the planned rule on children, and explain why the p lanned regulation is preferable to other potentially effective and reasonably feasible alter natives considered by the Agency.

EPA interprets Executive Order 13045 as applying on ly to those regulatory actions that are based on health or safety risks, such that the analysis required under section 5-501 of the Order has the potential to influence the regulation . This proposed rule is not subject to Executive Order 13045 because it proposes approve a state rule implementing a Federa l program.

H. Executive Order 13211, Actions that Significantl y Affect Energy Supply, Distribution, or Use This rule is not subject to Executive Order 13211, Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, o r Use (66 FR 28355, May 22, 2001) because it is not a significant regulatory action under Exe cutive Order 12866.51 of 52

I. National Technology Transfer and Advancement Act Section 12(d) of the National Technology Transfer a nd Advancement Act of 1995 (“NTTAA”), Public Law No. 104-113, section 12(d) (1 5 U.S.C. 272 note) directs EPA to use voluntary consensus standards in its regulatory act ivities unless to do so would be inconsistent with applicable law or otherwise impractical. Volu ntary consensus standards are technical standards (e.g., materials specifications, test met hods, sampling procedures, and business practices) that are developed or adopted by volunta ry consensus standards bodies. The NTTAA directs EPA to provide Congress, through OMB, expla nations when the Agency decides not to use available and applicable voluntary consensus st andards.

This proposed rulemaking does not involve technical standards. Therefore, EPA is not considering the use of any voluntary consensus stan dards.

List of Subjects in 40 CFR Part 52 Environmental protection, Air pollution control, In tergovernmental relations, Oxides of nitrogen, Particulate matter, Reporting and recordk eeping requirements.

Authority : 42 U.S.C. 7401 et seq52 of 52

Dated: September 2, 2010 Stephen S. T uber, Acting Regional Administrator, Region 8.